Learning how to read the numbers on your green card comes down to telling two apart: the A-Number on the front, which identifies you as a person for the rest of your immigration life, and the 13-character document number on the back, which identifies only the piece of plastic in your hand. Everything else on the card, including the category code, the “Resident Since” date, and the machine readable zone, either points back to one of those two numbers or tells you something about your status rather than your identity.
The A-Number on the Front
The most prominent number on the front of the card sits next to the label “USCIS#.” That is your A-Number, or Alien Registration Number, printed without the leading “A.” It is a seven-, eight-, or nine-digit number assigned to you by the Department of Homeland Security, and it follows you for life.1U.S. Citizenship and Immigration Services. A-Number/Alien Registration Number/Alien Number (A-Number or A#)
The A-Number does not change when you renew the card, replace it, or naturalize. It appears on nearly every immigration form and every piece of correspondence USCIS sends you. When a form asks for your “Alien Registration Number” or “A-Number,” this is what it wants.
One quirk trips people up. If your A-Number has fewer than nine digits, USCIS pads it with a leading zero to make it nine. So “A12345678” becomes “A012345678” on forms that expect nine digits.2U.S. Citizenship and Immigration Services. USCIS Immigrant Fee Payment – Tips on Finding Your A-Number and DOS Case ID Older cards sometimes label the same field “A#” rather than “USCIS#,” but it’s the same number.
The Document Number on the Back
Turn the card over. Above the block of small text at the bottom, you’ll find a 13-character alphanumeric code. This is the document number. It identifies this specific physical card, and it changes every time USCIS issues you a new one, whether through renewal, replacement, or a change in status.3U.S. Citizenship and Immigration Services. Receipt Number
You’ll hear this number called several things: the “green card number,” the “receipt number,” or the “permanent resident number.” They all refer to the same 13-character code. It corresponds to the approved petition that produced your current card.
What the 13 Characters Mean
The document number follows a consistent pattern. The first three letters identify the USCIS facility that processed your case:
- EAC or VSC: Vermont Service Center
- WAC or CSC: California Service Center
- LIN or NSC: Nebraska Service Center
- SRC or TSC: Texas Service Center
- MSC or NBC: National Benefits Center
- YSC: Potomac Service Center
- IOE: electronically filed or electronically processed case
After the three-letter prefix, the next two digits are the federal fiscal year (which starts October 1) when USCIS received the case. The three digits after that are the computer workday within that fiscal year. The final five digits are a unique case identifier. So SRC2004551423 means the Texas Service Center received the case in fiscal year 2020, opened it on the 45th workday, and assigned case number 51423.3U.S. Citizenship and Immigration Services. Receipt Number
Which Number to Use Where
Getting the wrong number in the wrong field is the single most common mistake cardholders make. The rule is simple: forms that ask about you want the A-Number, and forms that ask about the card want the document number.
Form I-9 for a new job. Your green card is a List A document, proving both identity and work authorization at once.4USCIS. List A Documents That Establish Identity and Employment Authorization In Section 1, you enter your A-Number. In Section 2, your employer records the 13-character document number from the back along with the card’s expiration date. Reversing the two is one of the most common I-9 errors on file.
Checking case status online. The USCIS Case Status tool takes the 13-character receipt number. If you’re tracking a pending application tied to your current card, that’s the number you enter, with any dashes removed.5U.S. Citizenship and Immigration Services. Checking Your Case Status Online
Replacing a lost, stolen, or expired card (Form I-90). The application uses your A-Number as the primary identifier.6U.S. Citizenship and Immigration Services. Instructions for Application to Replace Permanent Resident Card The filing fee is $465 by paper or $415 online, with no fee if USCIS caused the error requiring replacement or if you’re a teenager whose card expires before your 16th birthday and meets certain conditions.7U.S. Citizenship and Immigration Services. USCIS Fee Schedule Fee waivers are available for qualifying applicants.
Applying for citizenship (Form N-400). The naturalization application asks for your A-Number and the “Resident Since” date from the front of your card. If the card has expired or been lost, replace it first so you’re working from accurate information.
The Category Code
The “Category” field on the front is not a number, but people often lump it in with the numbers because it looks like one. It’s a short alphanumeric code showing the immigration classification under which you were granted permanent residence.8Office of Homeland Security Statistics. Immigrant Classes of Admission Common examples:
- IR1: Spouse of a U.S. citizen (new arrival)
- IR2: Child of a U.S. citizen (new arrival)
- IR5: Parent of an adult U.S. citizen (new arrival)
- CR1: Conditional resident spouse of a U.S. citizen (marriage less than two years old at approval)
- F11: Unmarried son or daughter of a U.S. citizen (family preference)
- E11: Priority worker (employment-based first preference)
Codes ending in “1” generally indicate a new arrival admitted with an immigrant visa. Codes ending in “6” or “7” typically indicate someone who adjusted status from within the United States. A “CR” prefix means the card is conditional, which changes how you renew it.
The Resident Since Date
The “Resident Since” date shows when you officially became a lawful permanent resident. For most people, this is the date USCIS approved adjustment of status or the date of admission with an immigrant visa.9U.S. Citizenship and Immigration Services. USCIS Policy Manual Volume 12, Part D, Chapter 2
This date is the starting point for calculating naturalization eligibility. Most permanent residents need five years of continuous residence, or three if married to a U.S. citizen, before applying for citizenship, and the clock starts here. If the date on your card looks wrong, contact USCIS before filing rather than guessing which date to use.
The Machine Readable Zone
The block of small text at the bottom of the back of the card is the machine readable zone, or MRZ. It runs three lines of 30 characters, formatted so scanners at airports and border crossings can read it.
The first line starts with a code showing whether you are a standard permanent resident (C1) or a permanent resident commuter living in Canada or Mexico (C2). It also contains your A-Number and your 13-character document number embedded within the string. The second line encodes date of birth, gender, expiration date, and country of birth in compressed year-month-day format. The third line contains your name along with your father’s and mother’s first initials. Blank spaces are filled with angle brackets as placeholders.
You won’t normally need to decode any of this. If someone points at the back of your card and asks for the document number, they want the 13-character code printed above the MRZ, not one of the long strings inside it.
Expiration Date: Standard vs. Conditional
One boundary worth flagging, because it changes what “renewal” even means. Look at the expiration date on the front. A standard card is valid for ten years and can be renewed by filing Form I-90. A conditional card is valid for two years and cannot be renewed at all.10U.S. Citizenship and Immigration Services. Conditional Permanent Residence Instead, you must file Form I-751 to remove the conditions during the 90-day window immediately before the card expires.11U.S. Citizenship and Immigration Services. When to File Your Petition to Remove Conditions Missing that window without filing means losing permanent resident status and possible removal proceedings. Late filing is possible but requires a written explanation of the delay.
So when you read your card, start with the two numbers that matter: A-Number in front, document number in back. Then check the category to see how you got your status, the “Resident Since” date to know when your naturalization clock started, and the expiration date to know whether you’re on a two-year or ten-year cycle. Those five items answer nearly every question a form or an employer will ever ask about the card.